Laboratory for Nuclear Science

Estimating Isotope Shifts for $^{227}$Th and $^{229}$Th in Th$^{3+}$: 5F$_{5/2} \rightarrow$ 6D$_{5/2}$ Transition

Wed, 25 Feb 2026 00:00:00 GMT

Estimating Isotope Shifts for $^{227}$Th and $^{229}$Th in Th$^{3+}$: 5F$_{5/2} \rightarrow$ 6D$_{5/2}$ Transition Lam, P. Y. Ian; MohanMurthy, Prajwal \textbf{Motivation:} Accurate spectroscopic information for isotopes of $^{224-232}$Th are critical for experimental programs investigating such thorium isotopes as candidates for next-generation nuclear optical clocks and as platforms for searches of symmetry-violating effects. Direct experimental data on isotope shifts in the $\text{Th}^{3+}:5F_{5/2} \to 6D_{5/2}$ line at $690$ nm are sparse, with measurements available only for $^{229}\text{Th}$ and $^{230}\text{Th}$ relative to the reference isotope $^{232}\text{Th}$.\\ \textbf{Method:} To address this gap, we employed a King-plot analysis comparing the well-characterized isotope shifts of the $\text{Th}^{+}$ transition at $583.9$ nm to the limited data available for the $690$ nm transition of $\text{Th}^{3+}$. Using nuclear structure information on mean-square charge radii and nuclear quadrupole deformations, we extracted the field-shift constant $F_{690}$ and mass-shift constant $M_{690}$ for the $690$ nm transition. We subsequently calculated the missing isotope shifts by incorporating published values of $\delta\langle r^2\rangle$ where available and estimating $\delta\langle r^2\rangle$ for unmeasured isotopes using nuclear quadrupole deformation coefficients $\beta_2$ from the FRDM model.\\ \textbf{Key Results:} The calculated isotope shifts for the $\text{Th}^{3+}:5F_{5/2} \to 6D_{5/2}$ transition relative to $690~$nm transition of $^{232}\text{Th}$ are: \begin{align} \delta\nu^{224,232}_{690} &= -29296(5585) \text{MHz} \nonumber\\ \delta\nu^{225,232}_{690} &= -25840(4930) \text{MHz} \nonumber\\ \delta\nu^{226,232}_{690} &= -22113(4219) \text{MHz} \nonumber\\ \delta\nu^{227,232}_{690} &= -18631(6238) \text{MHz} \nonumber\\ \delta\nu^{228,232}_{690} &= -14970(6181) \text{MHz} \nonumber\\ \delta\nu^{231,232}_{690} &= -3742(715) \nonumber\text{MHz} \end{align} Our results for the isotopes of $^{227,228}$Th use experimental $\delta\langle r^2\rangle$ values, whereas the remaining ones use theoretical values of $\delta\langle r^2\rangle$ calculated from quadrupole deformation coefficients. These results provide essential spectroscopic data for future precision measurements with thorium isotopes in various ionized states. This work is supported by BNL award #460913, a Phi Kappa Phi Fellowship, and generous support from Prof. R. P. Redwine and MIT LNS.

Identifying ideal nuclei in which to search for CP violating moments: Necessity to populate nuclear levels and characterize their nuclear deformation

Tue, 24 Jan 2023 00:00:00 GMT

Identifying ideal nuclei in which to search for CP violating moments: Necessity to populate nuclear levels and characterize their nuclear deformation Mohanmurthy, Prajwal; Winger, Jeff New sources of CP violation, beyond the known sources in the standard model (SM) via the CKM matrix, are required to explain the baryon asymmetry of the universe. Measurement of P,T violating moments, such as the electric dipole moment (EDM) or the magnetic quadrupole moment (MQM), of sub-atomic particles like the neutron or the electron as well as of atoms, serves as powerful tools with which to probe sources of CP violation. Quadrupole and octupole deformation of nuclei can significantly enhance the atomic EDM by many orders of magnitude compared to that with a spherical nucleus. In this white paper, we identify deformed isotopes in which to measure an EDM or an MQM. Furthermore, we also clearly identify a subset of these isotopes where measurements involving characterization of their level scheme and nuclear deformation parameters are necessary. (A section in the low energy white paper of the 2022 NSAC Long Range Planning exercise.)

False EDM effects in PSI nEDM: Leakage Currents and Background Asymmetries

Wed, 15 Sep 2021 00:00:00 GMT

False EDM effects in PSI nEDM: Leakage Currents and Background Asymmetries Mohanmurthy, Prajwal The Paul Scherrer Institute Neutron Electric Dipole Moment (PSI nEDM) experiment is a room temperature experiment using the Ramsey technique of separated oscillating fields to search for a permanent electric dipole moment in neutrons. The PSI nEDM experiment achieved a statistical sensitivity of d_n < 1.1 * 10^{-26} e.cm using data collected from 2015 to 2016. The magnetic field produced by currents flowing near the precession chamber couple to the spin of the stored neutrons. Currents which are correlated with the electric field may induce a false measurable EDM. Candidates for currents which are correlated with high voltage are leakage currents originating from the high voltage system used to apply a strong electric field to the stored neutrons. A study using finite element analysis of the possible pathways taken by the leakage currents is discussed. Similarly, background neutron counts may also lead to false EDM signals. But such backgrounds would also need to be correlated with the neutron spin state, high voltage state, LF signal, and spin-flipper states. We present a study here which constrains the false EDMs arising from such leakage currents to d^(False)_{n/Hg} < 4*10^{-28} e.cm, and from background asymmetries to d^(False)_{n-Backgrounds} < 3.6*10^{-65} e.cm.

A Search for Mirror Neutron Oscillation Using the nEDM Apparatus at PSI: Details about computing the mean time between collisions and extraction of the limit on the n-n' oscillation time

Wed, 15 Sep 2021 00:00:00 GMT

A Search for Mirror Neutron Oscillation Using the nEDM Apparatus at PSI: Details about computing the mean time between collisions and extraction of the limit on the n-n' oscillation time MohanMurthy, Prajwal Baryon number violation is a key ingredient of baryogenesis. Since the famous parity violation paper of Lee and Yang, it has been hypothesized that there could also be a parity conjugated copy, in the context of the weak interaction, of the standard model particles. The existence of such a mirror universe has specific testable implications, especially in the domain of neutral particle oscillation, viz. the baryon number violating neutron to mirror-neutron (n-n')oscillation. It was shown that such n-n' oscillations could happen rapidly with an oscillation time as small as a second. Consequently, there were many experiments which searched for n-n' oscillation, but which have so far reported finding no evidence of n-n' oscillation. Even though the experiments report having found no evidence of n-n' oscillation, reanalysis of some of these results have identified three particular anomalies which could point to the detection of n-n' oscillation. All but one of these efforts were conducted at the Institut Laue-Langevin in Grenoble, France, with the most recent search having been conducted at the Paul Scherrer Institute in Villigen, Switzerland. The results from this latest effort were announced in Phys. Lett. B 812, 135993 (2021). This search for n-n' oscillation involved measuring the number of neutrons after storage for a time period under the influence of zero magnetic field or a finite magnetic field. The neutron counting measurables were combined with the mean time between collisions of the stored Ultra Cold Neutrons (UCNs) to yield constraints on the n-n' oscillation time constant. In this paper, additional details regarding the analysis, i.e. the method of estimating mean time between collisions, as well as the numerical technique of extracting the constraint upon the n-n' oscillation time constant from the neutron counting measurables, is described. We obtained (t^*_s=180s)=0.0628(27)s, (t^*_s=380s)=0.0756(30)s, and (/)(t^*_s=180s)=0.104(10)s, (/)(t^*_s=380s)=0.120(10)s.

Characterization of PSI nEDM apparatus: T1, T*2, and UCN storage lifetime

Mon, 21 Jun 2021 00:00:00 GMT

Characterization of PSI nEDM apparatus: T1, T*2, and UCN storage lifetime MohanMurthy, Prajwal The neutron electric dipole moment (nEDM) experiment, located at the Paul Scherrer Institute (PSI), employs the Ramsey technique of separated oscillating fields, at room temperature, to search for a permanent EDM in the neutron. Neutrons with very low energy are produced in the PSI ultracold neutron (UCN) source, which are polarized by allowing them to pass through a 5 T strong magnetic field produced by a superconducting magnet. The UCNs are then stored in a chamber, where they are subject to the Ramsey technique. Manipulation of magnetization of the ensemble of stored UCNs is governed by Bloch equations, which describe the Larmor precession under the influence of a magnetic field, and involve two channels of depolarization; the transverse depolarization and the longitudinal depolarization. The time constants for longitudinal and transverse depolarization, T1 and T*2, respectively, were measured in the PSI nEDM apparatus at the beginning of the nEDM data taking schedule. T1 and T*2 play an important role in optimizing the period of free spin-precession in the Ramsey technique. We report the relaxation time constants as T1=(5770\pm420) s and T*2=(1550\pm22) s, for the UCNs from the PSI UCN source in the PSI nEDM apparatus. These values of T1 and T*2 are consistent with values reported in EPJ Web Conf. 219, 02001 (2019).

Supplementary material for Gamma-ray Constraints on Decaying Dark Matter and Implications for IceCube

Sun, 04 Dec 2016 00:00:00 GMT

Supplementary material for Gamma-ray Constraints on Decaying Dark Matter and Implications for IceCube Cohen, Timothy; Murase, Kohta; Rodd, Nicholas; Safdi, Benjamin; Soreq, Yotam Supplementary data to "Gamma-ray Constraints on Decaying Dark Matter and Implications for IceCube". This data contains limits on final states, models, and also flux vs TS tables.

Supplementary material for NPTFit

Wed, 30 Nov 2016 00:00:00 GMT

Supplementary material for NPTFit Rodd, Nicholas; Safdi, Benjamin; Mishra-Sharma, Siddharth Supplementary material for use with NPTFit (https://github.com/bsafdi/NPTFit/) This data contains a subset of the Fermi-LAT gamma-ray data, and models for describing the data. The full Fermi-LAT data can be accessed here: http://fermi.gsfc.nasa.gov/ssc/data/access/ NOTE: New file updates the Fermi diffuse model to fix an error in the exposure correction of that template. NOTE: Small correction to template normalization and point source mask radius applied, February 15, 2019.

The Desktop Muon Detector: A simple, physics-motivated machine- and electronics-shop project for university students

Fri, 26 Aug 2016 00:00:00 GMT

The Desktop Muon Detector: A simple, physics-motivated machine- and electronics-shop project for university students Axani, Spencer N.; Conrad, Janet M.; Kirby, Conor The supplementary material for the Desktop Muon Detector.

Cost Estimates for the KPipe Experiment

Wed, 01 Jul 2015 00:00:00 GMT

Cost Estimates for the KPipe Experiment Conrad, Janet M.; Axani, Spencer N.; Collin, Gabriel; Shaevitz, Michael H.; Spitz, Joshua; Wongjirad, Taritree We present estimates for the cost of the KPipe experiment. Excluding the cost of civil engineering, the total cost comes to 4.6 million USD. This report supports statements in arXiv article 1506.05811.

An estimation of systematics for up-going atmospheric muon neutrino flux at the south pole.

Tue, 11 Aug 2015 00:00:00 GMT

An estimation of systematics for up-going atmospheric muon neutrino flux at the south pole. Collin, Gabriel A disappearance based sterile neutrino search requires knowledge of the neutrino flux at the detector. In IceCube, this this flux is provided by the interaction of cosmic rays in the atmosphere. An important property of the flux is its systematic uncertainty. This data release contains the atmospheric muon neutrino fluxes used for the IC-86 sterile neutrino analysis. The file 'neutrino_flux_spectrums.h5' is a HDF5 dataset which contains the systematic and statistical variations of the south pole up-going atmospheric muon neutrino flux. The method used to derive this neutrino flux, and a description of the file format is provided in the included 'tech_note.pdf' document. The 'usage_example.py' file is an example python script for using the data set.

Data Release for NuTeV nu_e Disappearance Analysis

Mon, 23 Jul 2012 00:00:00 GMT

Data Release for NuTeV nu_e Disappearance Analysis Conrad, J.M.; Shaevitz, M.H. Data Release for the NuTeV electron flavor disappearance study. See this document for instructions on incorporating the NuteV nu_e disappearance data into oscillation global fits.

DRAGON 3.06H Fission Rate Modifications With Tutorial

Fri, 13 Apr 2012 00:00:00 GMT

DRAGON 3.06H Fission Rate Modifications With Tutorial Jones, Christopher This is a modification to the reactor simulation code DRAGON 3.06H. The modification includes the modified files, a tutorial in PDF, and a sample input and output,